Carcinoma in situ

Cutaneous carcinoma in situ, also called Bowen's disease, is a clinical form of in situ squamous cell carcinoma of the skin. It occurs mainly on sun-exposed areas of fair-skinned elderly people (especially the face and legs), and may also occur on the trunk and vulva. Clinically it presents as asymmetric, well-demarcated scaly erythematous plaques with clear borders from adjacent normal tissue. It progresses slowly and may remain intraepithelial for years. Pathology shows full-thickness squamous cell abnormality: epithelial cell polarity is disordered, normal epithelial cells are replaced by atypical or multinucleated bizarre cells, with common keratinization and mitotic figures; the basement membrane remains intact, and follicular infundibular involvement is common.

Common Symptoms

Pernicious anemia; loss of appetite; cachectic facies; chest tightness; weight loss

Causes

Carcinoma in situ generally refers to severe atypical hyperplasia within the mucosal epithelial layer or epidermal layer, involving the full thickness of epithelium, but without breaching the basement membrane to infiltrate downward. Examples include carcinoma in situ of the cervix, esophagus and skin. Epithelial tissue covers the body surface and internal/external surfaces of organs, consisting of layers of epithelial cells and a basement membrane, beneath which lie stroma and dermis. In carcinoma in situ, cancer cells are confined to the epithelial layer and have not destroyed the basement membrane or invaded underlying stroma/dermis, and there is no infiltration or distant metastasis. It is therefore sometimes called "pre-invasive carcinoma" or "stage 0 cancer".

Treatment

Cryotherapy; curettage and cautery; photodynamic therapy

Prevention

Early symptoms are subtle; a slow-growing mass at the limbus or mild discomfort noticed incidentally should prompt hospital visit. Suspected cases should undergo tumor excision with pathology. If it recurs after surgery, re-operation can still be curative; the earlier the better. Carcinoma in situ generally refers to severe atypical hyperplasia within mucosal epithelium or epidermis, involving the full epithelial thickness but without breaching the basement membrane. Examples include cervical, esophageal and cutaneous carcinoma in situ. Because it is an early-stage cancer, early detection and active treatment prevent progression and yield good outcomes with little patient distress, so it is often excluded from major-illness insurance clauses. Common forms include cervical in situ squamous cell carcinoma, intraductal breast carcinoma, Paget's disease of the breast, Bowen's disease of skin, in situ transitional cell carcinoma of bladder, and in situ squamous cell carcinoma of larynx.

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Warm reminder: The above information is provided for health education reference only and cannot replace professional medical diagnosis. If you have related symptoms, please seek care at a regular hospital in time.